One Nation Under Law examines the creation of the court and follows it through the brink of the Civil War, paying particular attention to the fourth chief justice of the Supreme Court - John Marshall - and to his successor, Roger Taney. Marshall presided over one of the most famous cases before the court while Taney presided over one of the most infamous. In Marbury v. Madison (1803), Marshall found in an obscure case involving an unsigned judicial appointment the opportunity to assert the court's most important power: judicial review, which gave federal courts the right to strike down laws that clashed with the Constitution. In Dred Scott v. Sandford (1857), however, Taney, the next chief justice, exercised that same power against the national government - to protect slavery.